1. Field of the Invention
The present invention broadly relates to the determination of dermal absorption of vapors and, more particularly, is concerned with a method and system for exposure of the skin of a laboratory animal, such as a rat, to vapors while protecting the animal's respiratory tract from exposure.
2. Description of the Prior Art
It is conventional practice for individuals to take steps to protect their respiratory tracts when working in environments containing hazardous chemicals. For example, workers in certain operational environments in the Air Force commonly wear respiratory masks to minimize the opportunities for pulmonary uptake of hazardous compounds and in these instances it is important to determine if dermal absorption of these vapors can be hazardous. However, up to the present time, it has not been known what hazards are involved in dermal exposure to certain toxic chemicals when an individual in wearing only respiratory protection. Chemical compounds such as hydrazine, chemical warfare agents and fuel vapors fall in this category. The cautious and prudent practice is to error on the side of wearing more protective clothing than might be necessary in the absence of a scientific basis for doing otherwise. Unfortunately, heretofore, studies which might provide some basis for deciding the extent of worker protection necessary in environments containing various hazardous chemicals have generally been lacking.
At the present time no satisfactory system exists to investigate the penetration of the skin by gasses or vapors. Previous approaches to investigate dermal absorption of vapors in rodents have involved isolation of the head of the rodent in a separate chamber from the body using a rubber dam to separate the chambers. These attempts have been unsatisfactory because of the tendency of the rodent to struggle when restrained by the neck and because of the difficulty in completely preventing leaks of the chemical atmosphere from the body side of the chamber to the head side of the chamber.
Consequently, a need exists for a testing setup which would reliably and accurately determine the rate of dermal absorption in laboratory animals of various hazardous chemicals, without exposure via the animal's respiratory tract.